Conventionally, processing of color image data by a printer driver is classified broadly into the following three types: The first is a method (a high-quality mode) that includes operating on rendering instructions from an operating system to develop bitmap data in a multivalued bitmap area (multivalue rendering), and subjecting the entirety of the multivalued bitmap area to color processing (color correction processing, multivalued color conversion processing and binarization processing) at the conclusion of developing process of all rendering instructions.
The second is a method (RGB (Red, Green, Blue) high-speed mode) that includes applying color processing (color correction) to rendering instructions from an operating system, applying binarization processing to the original RGB data to thereby create a brush, subsequently developing bit data in a binary bitmap area (RGB binary rendering), and subjecting the binary bitmap area to color processing (binary color conversion) at the conclusion of processing of all rendering instructions.
The third is a method (CMYK (Cyan, Magenta, Yellow, Black) high-speed mode) that includes applying color processing (color correction and multivalued color conversion) to render instructions from an operating system, applying binarization processing to CMYK data created by the color conversion to thereby create a brush, and subsequently developing bit data in a binary bitmap area (CMYK binary rendering).
In the high-quality mode of the first method, the multivalued bitmap data is developed and the entirety of this area is subjected to color processing. As a result, a large memory storage capacity is used. Additionally, color processing and binarization processing are required to be executed pixel by pixel and processing efficiency is poor as a consequence.
In the RGB high-speed mode of the second method, CMYK data that is eventually printed is created from binarized RGB bitmap data. As a result, image quality declines because it is impossible to alter the UCR (whether black data is expressed by CMY inks or by K ink) balance.
In the CMYK high-speed mode of the third method, the quality of the printed image is approximately the same as that in the high-quality mode. This performance is considered to be close to that of the RGB high-speed mode. The CMYK high-speed mode, however, requires that a logical operation predicated on linear independence be performed in color space of CMYK that is not linearly independent, or specifically, that has been obtained by conversion from RGB color space. Consequently, it is difficult to obtain the original ideal results. Further, depending upon the printer driver, special processing is executed if a special logical operation occurs, or logical operations having a low frequency of appearance are processed leaving defective conditions as is. As a result, few products execute print processing with the mechanism of the CMYK high-speed mode.